com.fasterxml.jackson.xml.ser.XmlBeanSerializerModifier Maven / Gradle / Ivy

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Extension for Jackson (http://jackson.codehaus.org) to offer alternative support for serializing POJOs as XML and deserializing XML as pojos. Support implemented on top of Stax API (javax.xml.stream), by implementing core Jackson Streaming API types like JsonGenerator, JsonParser and JsonFactory. Some data-binding types overridden as well (ObjectMapper sub-classed as XmlMapper).
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package com.fasterxml.jackson.xml.ser;

import java.util.List;
import java.util.Map;

import javax.xml.namespace.QName;

import org.codehaus.jackson.map.AnnotationIntrospector;
import org.codehaus.jackson.map.JsonSerializer;
import org.codehaus.jackson.map.SerializationConfig;
import org.codehaus.jackson.map.introspect.AnnotatedMember;
import org.codehaus.jackson.map.introspect.BasicBeanDescription;
import org.codehaus.jackson.map.ser.BeanPropertyWriter;
import org.codehaus.jackson.map.ser.BeanSerializer;
import org.codehaus.jackson.map.ser.BeanSerializerModifier;
import org.codehaus.jackson.type.JavaType;

import com.fasterxml.jackson.xml.XmlAnnotationIntrospector;
import com.fasterxml.jackson.xml.util.XmlInfo;

/**
 * We need a {@link BeanSerializerModifier} to replace default BeanSerializer
 * with XML-specific one; mostly to ensure that attribute properties are output
 * before element properties.
 */
public class XmlBeanSerializerModifier extends BeanSerializerModifier
{
    /*
    /**********************************************************
    /* Overridden methods
    /**********************************************************
     */

    /**
     * First thing to do is to find annotations regarding XML serialization,
     * and wrap collection serializers.
     */
    @Override
    public List changeProperties(SerializationConfig config,
            BasicBeanDescription beanDesc, List beanProperties)
    {
        AnnotationIntrospector intr = config.getAnnotationIntrospector();
        for (int i = 0, len = beanProperties.size(); i < len; ++i) {
            BeanPropertyWriter bpw = beanProperties.get(i);
            final AnnotatedMember member = bpw.getMember();
            String ns = findNamespaceAnnotation(intr, member);
            Boolean isAttribute = findIsAttributeAnnotation(intr, member);
            bpw.setInternalSetting(XmlBeanSerializer.KEY_XML_INFO, new XmlInfo(isAttribute, ns));

            // Actually: if we have a Collection type, easiest place to add wrapping would be here...
            if (_isContainerType(bpw.getType())) {
                String localName = null, wrapperNs = null;

                QName wrappedName = new QName(ns, bpw.getName());
                QName wrapperName = findWrapperName(intr, member);
                if (wrapperName != null) {
                    localName = wrapperName.getLocalPart();
                    wrapperNs = wrapperName.getNamespaceURI();
                }
                /* Empty/missing localName means "use property name as wrapper"; later on
                 * should probably make missing (null) mean "don't add a wrapper"
                 */
                if (localName == null || localName.length() == 0) {
                    wrapperName = wrappedName;
                } else {
                    wrapperName = new QName((wrapperNs == null) ? "" : wrapperNs, localName);
                }
                beanProperties.set(i, new XmlBeanPropertyWriter(bpw, wrapperName, wrappedName));
            }
        }
        return beanProperties;
    }
    
    @Override
    public JsonSerializer modifySerializer(SerializationConfig config,
            BasicBeanDescription beanDesc, JsonSerializer serializer)
    {
        /* First things first: we can only handle real BeanSerializers; question
         * is, what to do if it's not one: throw exception or bail out?
         * For now let's do latter.
         */
        if (!(serializer instanceof BeanSerializer)) {
            return serializer;
        }
        return new XmlBeanSerializer((BeanSerializer) serializer);
    }

    /*
    /**********************************************************
    /* Helper methods
    /**********************************************************
     */
    
    /**
     * Helper method used for figuring out if given raw type is a collection ("indexed") type;
     * in which case a wrapper element is typically added.
     */
    private static boolean _isContainerType(JavaType type)
    {
        if (type.isContainerType()) {
            Class cls = type.getRawClass();
            // One special case; byte[] will be serialized as base64-encoded String, not real array, so:
            // (actually, ditto for char[]; thought to be a String)
            if (cls == byte[].class || cls == byte[].class) {
                return false;
            }
            // issue#5: also, should not add wrapping for Maps
            if (Map.class.isAssignableFrom(cls)) {
                return false;
            }
            return true;
        }
        return false;
    }
    
    private static String findNamespaceAnnotation(AnnotationIntrospector ai, AnnotatedMember prop)
    {
        for (AnnotationIntrospector intr : ai.allIntrospectors()) {
            if (intr instanceof XmlAnnotationIntrospector) {
                String ns = ((XmlAnnotationIntrospector) intr).findNamespace(prop);
                if (ns != null) {
                    return ns;
                }
            }
        }
        return null;
    }

    private static Boolean findIsAttributeAnnotation(AnnotationIntrospector ai, AnnotatedMember prop)
    {
        for (AnnotationIntrospector intr : ai.allIntrospectors()) {
            if (intr instanceof XmlAnnotationIntrospector) {
                Boolean b = ((XmlAnnotationIntrospector) intr).isOutputAsAttribute(prop);
                if (b != null) {
                    return b;
                }
            }
        }
        return null;
    }

    private static QName findWrapperName(AnnotationIntrospector ai, AnnotatedMember prop)
    {
        for (AnnotationIntrospector intr : ai.allIntrospectors()) {
            if (intr instanceof XmlAnnotationIntrospector) {
                QName n = ((XmlAnnotationIntrospector) intr).findWrapperElement(prop);
                if (n != null) {
                    return n;
                }
            }
        }
        return null;
    }
    
}